On 8/26/22 08:06, Kuppuswamy Sathyanarayanan wrote: > +struct tdx_report_req { > + __u8 subtype; > + __u64 reportdata; > + __u32 rpd_len; > + __u64 tdreport; > + __u32 tdr_len; > +}; Please do take a look at how the compiler ends up building that structure. If you sized things to "save space", the way the compiler treats that structure may surprise you. You might also want to look at how a 32-bit compile deals with it versus a 64-bit one.